If sec 4A = cosec (A — 15°), where 4A is an acute angle, find the value of A.

Question

Philoid · Accepted Answer

We are given that: sec 4A = cosec (A – 15°)

∴We can rewrite it as: cosec (90° - 4A) = cosec (A – 15°)

On comparing both sides, we get,

90° - 4A = A – 15 °

⇒ A + 4A = 90° + 15°

⇒ 5A = 105°

⇒ A = 21°